The Moon has a tail. A stream of sodium atoms trails away from it for hundreds of thousands of kilometres, and around new moon Earth passes through it.

Micrometeorite impacts and solar wind knock sodium off the surface, and sunlight pushes it downstream like a very thin comet tail. Around new moon the tail wraps toward Earth and gets focused by our gravity into a faint spot detectable with the right instruments. You can't see it; it's there.